\documentclass{article} 

\usepackage{pst-tree} 

\begin{document} 
\pstree{\Tr{\psframebox{Generation pour n=3}}}
{
	\pstree{\Tcircle{0}}
	{
		\pstree{\Tcircle{00}}
		{
			\Tcircle{000}
			\Tcircle{001}
		}
		\pstree{\Tcircle{01}}
		{
			\Tcircle{010}
			\Tcircle{011}
		}
	}
	\pstree{\Tcircle{1}}
	{
		\pstree{\Tcircle{10}}
		{
			\Tcircle{100}
			\Tcircle{101}
		}
		\pstree{\Tcircle{11}}
		{
			\Tcircle{110}
			\Tcircle{111}
		}
	}
}

\end{document}
